The present invention relates to a light pipe for transmitting light from a light source to an indicator window, e.g., to indicate that a certain system is in operation, especially in a personal computer.
It is conventional to provide instruments, such as personal computers for example, with an indicator window that is illuminated by a light source, to provide to a user a particular indication, e.g., an indication that the computer or some aspect thereof is in an "on" condition. For example, depicted in FIG. 1 is a personal computer C having an indicator window W.
It may occur, for certain design reasons, that the light source is not aligned with the indicator window. It is conventional in that event to provide a multi-angled light pipe formed of a light transmitting material such as plastic for transmitting the light from the light source to the indicator window. For example, depicted in FIG. 2 is a schematic view of a conventional light pipe 1 formed of a solid piece of plastic wherein light rays (shown in broken lines) from a lamp 2 are directed through a first section 3 of the pipe, reflect off a 45 degree smooth reflecting face 4, travel along a second pipe section 5, reflect off another 45 degree smooth reflecting face 6, and exit the pipe through a third pipe section 7 that extends through an opening or window 8 formed in an outer housing of the computer.
The cross section of the pipe may become changed in shape between the light inlet and outlet ends of the pipe. That is, the inlet end could be shaped to maximize light input, whereas the output end could be shaped to conform to the shape of the indicator window. For example, the first and second pipe sections 3, 5 could be of square cross section (see FIG. 3), and the third section 7 could be of an elongated rectangular shape (see FIG. 4) that corresponds to the shape of the window 8. However, as a result of the transformation in shape of the pipe, light reflected from the face 6 travels only along one half of the third section 7 (i.e., the right half in FIG. 2), whereby the light may be visible in only half of the viewing end of the light pipe.
Therefore, it would be desirable to provide a light pipe which eliminates that problem and enables the entire window to be illuminated with light, eliminating so-called "hot spots".